While TRAP was identified in the 1950s, ACP5 was cloned in the 1990s, an Acp5 knockout mouse was reported in 1996, and >3,000 articles are retrievable on PubMed using the terms “tartrate-resistant acid phosphatase” + “TRAP”, the immunopathology of SPENCD remains unclear. This evidence concerns the gene ACP5 and Spondyloenchondrodysplasia with immune dysregulation.